Insulated container

ABSTRACT

The invention relates a container formed from a blank. The container comprises a cup body having a side wall and a bottom wall cooperate with one another to form an interior space of the container. The side wall includes an inner surface. An insulative layer is bonded to the inner surface of the side wall. The side wall is constructed from a material having a melting temperature such that the insulative layer can be bonded directly thereto when heat is applied to the inner surface of the side wall.

FIELD OF THE INVENTION

This invention relates generally to the production of articles from paper and paperboard and to insulated articles made therefrom, and more particularly, relates to insulated cups made of paper and paperboard.

BACKGROUND AND DISCRIPTION OF THE INVENTION

Insulated cups and containers are widely used for serving hot and cold beverages and other food items. Such articles may be made from a variety of materials including polystyrene foam, double-walled containers, and multi-layered paper-based containers such as paperboard containers containing an outer foamed layer. Paper-based containers are often more desirable than containers made from styrene-based materials because paper-based materials are generally more amenable to recycling, are biodegradable and have a surface more acceptable to printing. However, multi-layered and multi-walled paper-based containers are relatively expensive to manufacture compared to polystyrene foam-based articles and often do not exhibit comparable insulative properties. Paperboard containers having an outer foam insulation layer are generally less expensive to produce than double-walled containers, but the outer surface is less compatible with printing. Corrugated and double-walled paperboard containers also generally provide suitable insulative properties, but are more complex and expensive to manufacture than single ply containers.

Therefore, there is a definite need to produce an economical insulated container made substantially of paperboard which has the required strength for convertibility, exhibits superior insulative properties, and contains a surface which is receptive to printing.

SUMMARY OF THE INVENTION

The present invention is directed to a low density paperboard material for use in producing insulated containers such as paper cups. The paper cup of this invention can be manufactured on an existing cup making machine requiring limited modifications to the cup making machine. Furthermore the insulation does not affect the sidewall seam, the cup rim or the cup rim seal.

Accordingly, one aspect of the present invention relates to a container comprising a sidewall having an inner surface. An insulative layer is affixed directly to the inner surface of the sidewall. The insulative layer includes a mating surface that is in direct contact with the inner surface of the sidewall. A bottom wall is sealably joined with the sidewall such that the sidewall and the bottom wall cooperate with one another to form an interior space of the container.

Another aspect of the present invention relates to a container formed from a blank. The container comprises a cup body having a side wall and a bottom wall cooperate with one another to form an interior space of the container. The side wall includes an inner surface. An insulative layer is bonded to the inner surface of the side wall. The side wall is constructed from a material having a melting temperature such that the insulative layer can be bonded directly thereto when heat is applied to the inner surface of the side wall.

A further aspect of the present invention relates to a container formed from a blank. The container comprises a cup body having a side wall and a bottom wall cooperate with one another to form an interior space of the container. The side wall includes an inner surface. An insulative layer is bonded to the inner surface of the side wall when the container is in the blank form. The insulative layer is bonded to the inner surface of the side wall by applying heat to one surface of the blank at melting temperature. Next, the insulative layer is directly contacted to the one surface of the blank so that insulative layer is bonded to the blank. Finally, the blank is winded to form the cup body.

BRIEF DISCRIPTION OF THE DRAWINGS

A full understanding of the invention can be gained from the following description of the preferred embodiments when read in conjunction with the accompanying drawings in which:

FIG. 1 is a perspective view of a container or paper cup constructed in accordance with the preferred embodiment of the present invention;

FIG. 2 is a cross sectional view of a wall portion of the container shown in FIG. 1;

FIG. 3 is an exploded view of a blank and an insulative layer;

FIG. 4 is a top plan view of FIG. 3 illustrating the insulative layer bonded to the blank;

FIG. 5 is a cross sectional view of FIG. 4;

FIG. 6 is a schematic view of a paper cup making machine used to construct the insulated cup depicted in FIG. 1; and

FIG. 7 is a side view in section of a portion of FIG. 6.

DETAIL DISCRIPTION OF THE INVENTION

While this invention is susceptible of embodiment in many different forms, there is shown in the drawings and will herein be described in detail preferred embodiments of the invention with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the broad aspect of the invention to the embodiments illustrated.

FIG. 1 is a perspective view of an insulated paper cup or container constructed in accordance with the preferred embodiment of the present invention. The container or paper cup 10 comprises a sidewall 12 having an inner surface 14. An insulative layer 16 is bonded to the inner surface 14 of the sidewall 12 as best depicted in FIG. 2. A bottom wall 18 is sealably joined with the sidewall 12 such that the sidewall 12 and the bottom wall 18 cooperate with one another to form an interior space 20 of the paper cup or container 10. The paper cup or container 10 can be manufactured on an existing cup making machine (shown in FIG. 6) requiring limited modifications to the cup making machine. Furthermore, the insulative layer 16 does not affect the sidewall seam 22, the cup rim or top end 24.

The container or cup 10 is intended for heated fluids and therefore, it is generally desirable to apply the insulative layer 16 on the inner surface 14 of the side wall 12. However, for chilled fluids (i.e. iced or cold drinks) which outer condensation is an issue, inner and outer surfaces of the side wall may be protected by the insulative layer 16 or alternatively, the inner and outer surfaces may be coated accordingly.

Testing of the thermal performance of the container or paper cup 10 demonstrates notably good insulative properties. The average time a person could hold a paper cup made was from 15 minutes compared to 30 second for the non-insulated container or paper cup 10.

The insulative properties of the container or paper cup 10 are determined by measuring the sidewall temperature of the paper cup 10 containing a hot liquid. A maximum value of sidewall temperature for the container or paper cup 10 containing a hot liquid is typically specified for an insulated paper cup. The sensory perception of heat is dictated by skin tissue exposed to the hot cup sidewall 12 for a period of time. Tissue temperature is a function of the heat flow to the tissue from the paper cup and the internal heat dissipation within the tissue. The heat flow to the tissue is a combination of several factors including the thermal properties of the paperboard, the temperature of the liquid, and the contact resistance between the tissue and the outer wall of the cup. The container or paper cup rigidity and surface roughness (i.e. texture) is also believed to contribute to the sensory perception of heat by influencing the effective contact area between the cup sidewalls and the tissue.

Turning to FIG. 3 now, an exploded view of a blank 30 and the insulative layer 16 is illustrated. The blank 30 includes an interior surface 32 and an exterior surface 34. In a commercial scale operation, the blank 30 is die-cut from a paperboard stock in roll form into a sectorial shape blank. The insulative layer 16 is substantially sized corresponding to the size of the blank 30 and is affixed directly to the interior surface 32 of the blank. The insulative layer 16 includes a mating surface 36 that is bonded to the interior surface 32 of the blank 30 as clearly illustrated in FIG. 4. It can be seen that the interior surface 32 of the blank 30 is substantially covered by the insulative layer 14. As will be described below in greater detail, the insulated blank 40 is converted to a paper cup on a commercial cup making machine with existing tooling.

The insulative layer 14 is applied to the interior surface 32 by methods such as thermoplastic welding, pressure sensitive adhesive, and ultrasonic welding. These methods as well as other methods that are well known in the art could be employed on the commercial cup forming machine. The insulative layer 14 made of materials that generally comprises of, but not limited to, polyolfin, polystyrene, polypropylene, foamed polyolfin, or foamed polystyrene. The exterior surface 34 is often carrying printing indicia /designs applied directly to thereto. The insulative layer 14 has a thickness in a range of about 0.001″ to about 0.25″. The thickness of the insulative layer 14 is generally higher than the thickness (caliper) of the blank 30 as clearly depicted in FIG. 5.

The blank 30 made of materials that generally comprises of, but not limited to a paperboard web having a basis weight ranging from about 100 to about 300 lbs/3000 ft². The paperboard web products used to manufacture paper cups are particularly dimensioned to contain generally 8-24 ounces of fluid. The internal base diameter of these paper cups are generally from about 2¼ inches to 3 inches. However, it is to be appreciated that low density paperboard according to the present invention may find utility in a wide range of applications and product dimensions where properties of thermal insulation are desirable.

For paperboard web according to the present invention, it is preferred that the paperboard web be formed so as to exhibit an average (i.e. average of Machine Direction (MD) and Cross Direction (CD)) internal bond strength of at least about 100×10⁻³ ft-lb_(f). This minimum internal bond together with other paperboard properties is believed to be needed so that the paperboard is successfully converted into cup shapes and similar articles without significant adverse effects caused by the converting operations. Among these adverse effects are so-called “buckles” which can appear along the height of a cup during the process of cup forming where polyethylene-coated paperboard develops small ripple-like deformations as the paperboard is wrapped around a mandrel to form the cup wall.

In addition, multi-ply paperboard webs exhibit increased insulative properties compared to conventional single ply paperboard webs and are significantly less expensive to produce than multi-layered paperboard products or paperboard products containing a foamed outer coating. The low density paperboard material may therefore be converted into cups and other insulated containers on conventional processing equipment with minimal loss in machine speed, and no tendency to form buckles and other irregularities in the converting operations.

Any suitable insulative layer 16 or barrier coating may be used to complete the product for conversion into a thermally insulated container such as a paper cup. Although low density polyethylene insulative layer are used for many such products and are preferred for use in the present invention, natural and synthetic chemical systems such as starch-based coatings and polyvinyl alcohol-based coatings may also be used as well as pigmented coatings containing inorganic or organic pigments such as clay, carbonate, and latexes, so long as they provide sufficient layer or barrier or other properties for the intended application. The insulative layer or coating(s) may be applied by conventional means, and in the case of polyethylene may be applied to the low density board surface by an extrusion lamination or by laminating a pre-formed film. The thickness of the coating may generally range from about 0.1 to about 35 mil, and is preferably about 1.5 mil on the inside surface of the container or cup.

Again, it is to be appreciated that low density paperboard according to the present invention may be used to make a range of potential products including, but not limited to, cups and other paperboard containers formed to hold warm, hot, or cold material where there is a need for insulation and at least short-term barrier properties. Also, when used to make paper cups, the bottom section is normally a flat separate piece and may or may not be formed from low density insulated paperboard made according to the present invention, depending on economics and other factors.

As described above, the container or paper cup 10 is a truncated cone shape paper cup that is constructed from the insulated blank 40 as depicted in FIG. 3. It is a commercial reality that some conventional cup forming machinery is designed to accommodate the use of a narrow range of caliper (thickness) of the blank 30. Because insulated blank 40 according to the present invention may be thicker than standard cup stock (for a given basis weight), the increased caliper may cause manufacturing issues potentially requiring new or modified machine tooling. In particular, a mandrel incorporating a relief area for the insulative material could be used to produce both an insulated cup and non-insulated cup. One of the advantages of the present invention is that neither cup forming machinery nor cup forming machine operating conditions need to be adjusted when changing from the production of insulated container or cup 10 to the standard non-insulated container or cup.

It is generally known that the side seam 22 of the container or paper cup 10 is thicker than the side wall 12 of the container or paper cup 10. One of the techniques used in manufacturing process to reduce the thickness in the side seam area is that the side seam 22 is exposed to a relatively high pressure (approximately 200 psi or greater), which will permanently compress the side seam of the container or paper cup 10 and allowing it to be used in the conventional machine tooling. The thickness of the side seam may be reduced to at or near conventional paperboard caliper levels (generally about 20 mil). This processing step is generally referred to in the art as “crimping” and may be considered a pretreatment of the finished low density paperboard (i.e., paperboard that has been coated) to facilitate its use in forming paper cups and other paperboard containers having one or more lap seams. In the present invention, there is no need to cover the side seam area with the insulative layer 16.

Before turning to FIG. 6, FIG. 7 illustrates the manner in which device 60 is used to apply the insulative layer 16 onto the inner surface 32 of the blank 30. In operation, the blank 30 is transferred by the belt 74 to the heater 76. At this stage, the interior surface 32 of the blank 30 is heated to proximately melting temperature. The interior surface 32 is coated with a layer of low density polyethylene and thus, when heated, the polyethylene layer is reached its melting temperature. The blank 30 is then moved onto the insulative material roll 78. The insulative web roll 77 is die cut, by a die cutter 75, to a geometrical shape that correspond to the shape of the blank 30. The insulative layer 16 is then bonded to the interior surface 32 of the blank 30. The hot surface of interior surface 32 permits the mating surface 36 to be partially melted onto the blank 30. The insulated blank 40 is then transferred to the portion of the cup making machine 50.

FIG. 6 illustrates the process of constructing the container or paper cup 10 from the blank 30. The cup making machine includes a mandrel turret 52, a transfer turret 54 and a rimming turret 56 mounted on a frame 58. The mandrel turret 52 is rotated in a step by step or indexing manner into alignment with each of the surrounding work stations 60, 62, 64, 66, 68, and 70, and 72. The mandrel 74 is stepped to a bottom reformer station 62 where the edges of the bottom blank 30 are folded outwardly. The mandrel turret 52 is then stepped into alignment with the transfer turret 54 where the insulated blank 30 is transferred from a hopper 80 to a position beneath the mandrel 52. The insulated blank 30 is folded about the mandrel 54; the edges of the bottom blank 30 are heated, overlapped and sealed along the seam by the seam clamp assembly 61. The mandrel 52 is then stepped in sequence to a bottom heat station 68; a roller in-curl station 46 and a bottom finish station 70.

Once the bottom blank 30 is formed and sealed, the paper cup is transferred to a discharge station 72 where it is transferred to a rimming turret 84, rotated to a lube station 64 and then rotated to a rimming precurl station 86 where the upper lip of the side wall is curled outwardly. From that station the paper cup is indexed to a rimming finish curl station 82 which finishes the curl portion along the top of the cup to make an attractive edge. The cup is then moved to a cup blow off station 88 for removal of the finished cup.

While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from its scope. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed, but that the invention will include all embodiments falling within the scope of the appended claims. 

1. A container comprising: a sidewall having an inner surface; an insulative layer affixed directly to the inner surface of the sidewall, wherein the insulative layer includes a mating surface that is in direct contact with the inner surface of the sidewall; and a bottom wall sealably joined with the sidewall wherein the sidewall and the bottom wall cooperate with one another to form an interior space of the container.
 2. The container of claim 1 wherein the side wall is made of a low density paperboard material.
 3. The container of claim 2 wherein the paperboard layer having a material exhibits internal bond strength of at least about 100×10⁻³ ft-lb_(f).
 4. The container of claim 1 wherein the insulative layer is bonded onto the inner surface of the sidewall.
 5. The container of claim 1 wherein the insulative layer is bonded to the inner surface of the side wall when the inner surface is heated to a melting temperature.
 6. The container of claim 1 wherein the insulative material substantially covers the inner surface of the side wall with the exception of a top end and the side seam area.
 7. The container of claim 1 wherein the insulative layer is made of a low density polyethylene.
 8. The container of claim 1 wherein the insulative material has a thickness ranging from about 0.001 to about 0.25 inches.
 9. The container of claim 1 wherein the container comprises a paper cup used to hold hot liquid.
 10. A container comprising: a side wall having an inner surface; an insulative layer bonded to the inner surface of the side wall; and a bottom wall sealably joined with the side wall wherein the side wall and the bottom wall cooperate with one another to form an interior space of the container.
 11. A blank for forming a container, wherein the container comprises: a cup body having a side wall and a bottom wall cooperate with one another to form an interior space of the container and wherein the side wall includes an inner surface; and an insulative layer bonded to the inner surface of the side wall wherein the side wall being constructed from a material having a melting temperature such that the insulative layer can be bonded directly thereto when heat is applied to the inner surface of the side wall. 